The strap part that extends between at least one side of the diaper closure and the actual diaper is typically a laminate that has at least one substrate layer and an elastic film bonded to the substrate layer and is elastically stretchable in a stretch direction at least in the region of the elastic film. The laminate has an inner end for attachment to the diaper and an outer end for the closure. The outer end has a narrower width transverse to the stretch direction than the inner end. In an elastic region between the inner and outer ends, the substrate layer is joined to the elastic film by a plurality of parallel adhesive strips that extend transverse to the stretch direction. Such a diaper part is in practice frequently also referred to as a diaper ear (back ear laminate).
An elastic diaper part having these features is known for example from WO 2006/124337. The adhesive joining the elastic film to the substrate layer made for example of a nonwoven is formed by a plurality of parallel and spaced adhesive strips that extend transverse to the stretch direction. Compared to surface bonding, such an array improves the elastic stretching properties of the laminate. Typically, the elastic region of the diaper part is mechanically activated by stretching. The application in strips of the adhesive improves the activation capability and the effectiveness of the activation. Within the known measures, the adhesive strips of the array all have the same width and are set at the same uniform spacing. In fact in WO 2006/124337, the width of the adhesive strips and the spacing between the strips have a fixed ratio specified within a range between 0.33 and 1.0.
US 2011/0151739 (EP 2,158,888) describes a laminate from which diaper parts can be stamped in a multi-web stamping process. The laminate has an elastic substrate film and nonwoven cover layers that are adhered to each other. It also has regions surface-bonded to each other and strip-shaped adhered regions. The adhesive strips form a pattern that comprises adhesive strips of varying width and/or arranged with varied spacing. The array thus has no relationship to the shape of the diaper parts stamped out from the laminate.
The prior-art laminates are distinguished by satisfactory stretching properties if the stretching measurements are made on laminate strips of constant width. In a tensile test on test pieces, which are typically standardized with regard to their dimensions, stretching properties can be uniformly measured.
In the case of diaper parts that are manufactured as so-called diaper ears and have an inner wide attachment end for attachment to a diaper and a narrow outer end for a closure, it has been observed that the elongation is not uniform when the laminate is stretched in the stretch direction. At the narrow attachment end, the elastic region of the diaper part is subject to a greater tensile stress and stretches more than the elastic region of the laminate adjacent the wide attachment end. Near the wide attachment end, better stretching is required, while on the outer end a higher strength is desirable.